Methods and devices providing transmyocardial blood flow to the arterial vascular system of the heart

ABSTRACT

This invention relates to methods and devices providing transmyocardial blood flow or coronary revascularization for the treatment of coronary atherosclerosis and resulting myocardial ischemia by increasing the flow of blood from one or more oxygenated blood sources within the patient to one or more sites selected in the arterial vascular system of the heart using a channel for maintaining and regulating blood flow therebetween. A valved conduit or a self-maintained channel is created between the left ventricle reservoir of oxygenated blood and the coronary artery distal to an area of obstruction by surgical and percutaneous methods. Preferably, the conduit or self-maintained channel integrally regulates the flow of blood between the oxygenated blood source and the site selected in the arterial vascular system of the heart wherein an increase in blood flow is desired.

FIELD OF THE INVENTION

This invention relates to methods and devices providing transmyocardialblood flow or coronary revascularization for the treatment of coronaryatherosclerosis and resulting myocardial ischemia. The inventionincreases the flow of blood from one or more oxygenated blood sourceswithin the patient to one or more sites selected in the arterialvascular system of the heart using a channel for maintaining andregulating blood flow therebetween. More particularly, a valve isinserted into a channel created and maintained between, or a valvedconduit is inserted between, the left ventricle reservoir of oxygenatedblood and the coronary artery distal to an area of obstruction.

BACKGROUND OF THE INVENTION

Heart disease is a major medical ailment wherein arteries becomenarrowed or blocked with a build-up of atherosclerotic plaque or clotwhich reduces flow to tissues downstream or “distal” to the blockage.When this flow reduction becomes significant, a patient's quality oflife may be significantly reduced. In fact, heart disease patients oftendie when coronary arteries become significantly blocked.

However, technology has been developed to treat patients with coronaryartery disease. Besides drug treatment, the two most common operativeprocedures used to treat symptomatic patients are: coronary arterybypass graft (CABG) surgery and percutaneous transluminal coronaryangioplasty (PTCA).

Conventional CABG surgery affixes a bypass graft between a port oraperture in a coronary artery wall distal to the blockage and apressurized arterial blood supply, such as the aorta, to provide aconduit for blood flow into the coronary artery to the ischemic areas ofthe heart. CABG surgery is generally initiated by directly exposing theheart to the surgeon by opening the patient's chest using knownsternotomy and retraction techniques that cut the sternum and spread therib cage open. Once the heart is exposed, the patient is connected to acardiopulmonary bypass (“CPB”) machine so that the blood supplycircumvents the heart. In this way, the heart is depressurized so thatapertures can be cut into the walls of the vessels for surgical graftattachment. The right atrium (or vena cava) and the aorta each isintubated with cannulas which are connected to an artificial pump andoxygenator. Once these major vessels are cannulated, the aorta is thenclamped proximally of the aortic bypass cannula, thereby isolating theaortic root and heart from the blood that is being circulated by theCPB. Cardioplegia is then delivered to stop the beating motion of theheart.

In one type of CABG method, the bypass grafting is achieved between theaorta and one of the three major coronary arteries or theirsub-branches, the left anterior descending artery (LAD), the circumflexartery (CIRC), or the right coronary artery (RCA). In such a case, asaphenous vein is usually taken from the patient's leg and istransplanted as a “homograft” to connect these vessels in order toprovide blood flow to the compromised area of the coronary circulation.Artificial grafts have also been disclosed as providing potentialutility for this purpose. An alternative CABG method uses the internalmammary artery (IMA) alone or in conjunction with the saphenous veingraft. The IMA is severed at a chosen location and is then connected toan aperture, in a coronary artery. The fluid connections between a graftand a vessel are commonly referred to as “anastomoses.” Once theanastomosis of the bypass graft is complete, the heart is resuscitatedand the patient is removed from CPB.

Although CABG surgery grafts have good long patency rates of about 60%to 90% over a ten year period, the isolation of the heart with the CPBand aortic cross-clamp carries a significant risk of mortality. It isbelieved that three critical determinants which affect outcomes of CABGsurgery are: (1) time the patient spends on bypass, (2) time the patientspends with a clamped aorta, and (3) the quality of the anastomoses. Itis generally believed that a CABG patient's operative and peri-operativemorbidity are directly related to how long the patient must be on CPB.During prolonged periods on CPB, there is a greater chance for air andplatelet embolization resulting from the artificial circuit. Forexample, such debris can embolize into the neurovasculature andpotentially cause a stroke. In analyzing the timing of individual CABGsteps against the backdrop of a patient's critical time on CPB, the timespent anastomosing the grafts to vessels emerges as a controllingfactor. Closely related to the time spent on CPB is a second CABGsuccess factor related to the extent and time of aortic cross-clamping.It is believed that the inherent crushing force from a cross-clampacross the bridge of the muscular aortic arch may be associated with ahigh degree of tissue trauma and structural damage. Additionally, bloodclots formed at or adjacent to the cross clamp, perhaps in conjunctionwith the tissue trauma of clamping, may also be a source of unwantedcomplications. In addition to the potential clinical complicationsassociated with CABG surgery is also the cost of the time-consumingprocedure.

In the PTCA procedures, a small incision is made in the patient's thighto introduce a catheter into the femoral artery. The catheter is guidedto the internal blockage site via x-ray visualization. The blockage isthen treated remotely by use of hydraulic pressure in the case ofballoon angioplasty wherein a balloon is inflated within the narrowedvessel to stretch or otherwise deform the blockage into a larger lumen.Or, in the case of atherectomy, other actuating means can be used tocause remote cutting or ablation of the blockage. In another approach, astent is used to scaffold open the blocked area of the artery. Althoughthese procedures are less traumatic than CABG surgery, the failure rateis often about 30-50% whereby the vessel narrows within a six monthperiod and must be treated again.

Due to the limitations with these operative techniques, alternatemethods have been proposed. For example, U.S. Pat. No. 5,655,548 byNelson et al. discloses open surgical and transluminal methods forsupplying long-term retrograde perfusion of the myocardium via a conduitdisposed between the left ventricle and the coronary sinus. Bloodejected from the left ventricle enters the coronary sinus during cardiacsystole. The outlet from the left ventricle to the coronary sinus mayinclude a one-way valve to prevent backflow from the coronary sinus intothe left ventricle during cardiac diastole. The long-term artero-venousfistula that is created, however, has the potential for edema or otherphysiologic effects.

Another alternate method is disclosed in international patentapplications: WO 97/27897, WO 97/27893, WO 97/13463, WO 97/13471, and WO97/27898; wherein a percutaneous, transluminal approach is describedwhich requires an adjacent cardiac vein to perform the procedure.Unfortunately, most coronary arteries do not have adjacent cardiac veinsand, thus, the disclosed approach may be limited in its ability toprovide full revascularization.

Another method is disclosed by Wilk in U.S. Pat. Nos. 5,429,144,5,287,861, 5,662,124 and 5,409,919, wherein an expandable stent isdisposed in the myocardium by a percutaneous approach through thecoronary artery requiring no incision through the chest. The methodrequires that the expandable stent be initially collapsed, ejected froma catheter into the myocardium, and subsequently expanded with aninflatable balloon in the myocardium. The expandable stent extends onlypartially through the myocardium, from the left ventricle of the heartor from a coronary artery, upstream of a vascular obstruction.Alternatively, the expandable stent can extend through the myocardiumbetween the left ventricle and the coronary artery, but is completelywithin the myocardium and not extending into either the left ventricleor coronary artery. The purpose of the expandable stent is to establishblood flow to the myocardium, and in some instances, to the coronaryartery. One design of the expandable stent is to collapse and closeduring systole. In an alternate design, the expandable stent can resistthe contractive pressure of the heart to remain open during systole topermit the flow of blood through the stent into the myocardium andcoronary artery. During diastole, the blood pumped into the coronaryartery through the expandable stent can be blocked from returning to theleft ventricle by an integrated, one-way valve.

Among the drawbacks in using the Wilk method is that the stent must beexpandable and any valve therein must be integral with the stent. Theexpandable stent is also sized to be only within, and not beyond, themyocardium. The expandable stent fails to accommodate changes in thethickness of the myocardium wall during the rhythmic contraction of theheart which, according to Feigenbaum's textbook of Echocardiography,changes from an average thickness of about 8 mm in diastole to about 13mm in systole. The transluminal approach disclosed by Wilk can also havedifficulty in delivering the expandable stent across coronary arterieswhich are substantially occluded. Approximately 60% of CABG surgeryprocedures are performed on totally occluded vessels where percutaneousaccess would not be feasible.

Ever since the discovery by Wearn, as reported in the “The Nature of theVascular Communications Between the Coronary Arteries and the Chambersof the Heart”, American Heart Journal, Volume 9, Number 2, 1933, thatthe myocardium is composed of a vast, sinusoidal network, people haveattempted to revascularize the heart muscle directly. In 1957, Massimoand Boffi reported experiments in the Journal of Thoracic Surgery,Volume 34, Number 2, with T-shaped tubes that were implanted directlyinto the myocardium in order to maintain a fluid channel between theleft ventricle and myocardium. Another approach pioneered by Vineberg,“Coronary Vascular Anastomoses by Internal Mammary Artery Implantation”,Canad. M. A. J., Volume 78, Jun. 1, 1958, focused on the implantation ofthe IMA directly into the myocardium. In 1965, Sen et al.,“Transmyocardial Acupuncture”, Journal of Thoracic and CardiovascularSurgery, Volume 50, Number 2, 1995, performed transmyocardialacupuncture which became the precursor to laser-assisted transmyocardialrevascularization (TMR) in 1986, wherein multiple laser pin holes aremade in the compromised myocardial area and into the left ventricle.However, these holes do not maintain a channel between the leftventricle and the native coronary circulation. Also, these holes are notmaintained in an open state once they are formed. It is surmised thatthe benefit of the TMR approach is that it stimulates angiogenesis (newvessel growth) rather than maintaining new channels of perfusion.

There have been several studies that clearly teach away from thetransmyocardial arterial revasculation described in the presentinvention. In a study similar to Sen et al., the authors Pifarre et al.,reported in “Myocardial Revascularization by TransmyocardialAcupuncture: A Physiologic Impossibility”, Journal of Thoracic andCardiovascular Surgery, Volume 58, Number 3, 1969, attempts torevascularize the myocardium by coring out sections of the muscle tocreate a left ventricle to myocardial connection. They concluded that “. . . no blood flow is possible from the ventricle to the myocardium.”

Another article “The Possibility of Myocardial Revascularization byCreation of a Left Ventriculocoronary Artery Fistula” by Ian Munro andPeter Allen, Journal of Thoracic and Cardiovascular Surgery, Volume 58,Number 1, 1969, discloses an attempt to revascularize an ischemicmyocardium by constructing a fistula between the cavity of the leftventricle and the coronary circulation. Two conclusions drawn from theexperimental results again teach away from the present invention.“First, any attempts to revascularize the wall of the left ventricledirect from the cavity of the ventricle are likely to be functionalfailures, even if technically successful . . . . In addition, there wasa failure of myocardial contractility and a rise in left ventricular anddiastolic pressure. It was concluded that operations designed torevascularize the myocardium direct from the cavity of the leftventricle make the myocardium ischemic and are unlikely to succeed.”

While other attempts have been made to reduce the complicationsassociated with “CABG” surgery through less-invasive, standard surgicalapproaches, they have been limited in their ability to fullyrevascularize the heart and provide a comparable degree of long-termsuccess. The prior art fails to disclose or fulfill the need fortransmyocardial blood flow or coronary revascularization using a beatingheart approach with either surgical or percutaneous techniques to createand maintain one or more regulated channels between the left ventricleand the arterial vascular system of the heart. The present inventionalso potentially eliminates the need for harvesting autologous bypassgraft material that can be in short supply, contributes to the morbidityof the CABG procedure, and can compromise the vascular system.

SUMMARY OF THE INVENTION

The present invention provides a method for increasing the flow of bloodto a selected site in a patient's arterial vascular system of the heart.The method includes, the steps of: creating a channel for blood flowfrom an oxygenated blood source to the selected site in the arterialvascular system of the heart; maintaining the channel in an openposition for blood flow through diastolic and systolic cycles of theheart; and regulating the blood flow in the channel to minimize bloodflow from the coronary vascular system to the blood source duringdiastolic cycle of the heart.

The present invention also provides a method for performing atransmyocardial coronary revascularization procedure for the treatmentof coronary atherosclerosis caused by an obstruction in the arterialvascular system. The method includes the steps of: creating a channelfor blood flow from an oxygenated blood source to the arterial vascularsystem distal to the area of obstruction; maintaining the channel in anopen position for blood flow through the diastole and systole cycles ofthe heart; and regulating the blood flow in the channel to minimizeblood flow from the arterial vascular system to the blood source duringthe diastolic cycle of the heart.

A method for treating an obstruction in a patient's cardiovascularsystem using a non-expandable conduit made of biocompatible material isalso provided by the present invention. The method includes the stepsof: inserting the conduit completely through the myocardium of thepatient's heart with one end of the conduit extending into the leftventricle and the other end of the conduit extending into the arterialvascular system distal to the area of obstruction; maintaining theconduit in an open position for blood flow through the diastolic andsystolic cycles of the heart; and regulating the blood flow in thechannel to minimize blood flow from the arterial vascular system to theleft ventricle during the diastolic cycle of the heart.

Another method provided by the present invention increases the flow ofblood to a selected site in a patient's arterial vascular system. Themethod includes the steps of: inserting one end of a conduit into theleft ventricle; inserting the second end of the conduit into thearterial vascular system at the selected site; maintaining the conduitin an open position for blood flow through the diastolic and systoliccycles of the heart; and regulating the blood flow in the conduit tominimize blood flow from the arterial vascular system to the leftventricle during the systolic cycle of the heart.

The present invention also includes conduits for maintaining a channelbetween an oxygenated blood source and a site in the arterial vascularsystem of the heart selected for delivering an increase of blood flowthereto. The conduit includes a tubular body having an inlet end andoutlet end between the blood source and selected site, respectively.Preferably, the conduit includes means for regulating the flow of bloodbetween the blood source and selected site. The conduit can includemeans for retaining the conduit in the myocardium with the inlet endextending into the left ventricle. Optionally, the conduit includesmeans for adjusting the conduit to the change of thickness of themyocardium during the heart cycle.

The present invention also provides a self-maintained channel createdbetween an oxygenated blood source and a site in the arterial vascularsystem of the heart selected for delivering an increase of blood flowthereto. The self-maintained channel maintains an open position duringat least a portion of the heart cycle. The self-maintained channelincludes an inlet end and outlet end between the blood source andselected site, respectively. Preferably, the self-maintained channelincludes an integral means for regulating the flow of blood between theblood source and selected site. Optionally, the self-maintained channelincludes a natural or synthetic valve positioned therein as theregulating means.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic cross-sectional view of a human heart showing aconduit inserted by a surgical method into a channel created from theleft ventricle to a coronary artery in accordance with the presentinvention;

FIG. 2 is a side view of another embodiment of the needle assemblyillustrated in FIG. 1 for creating and dilating an access port in themyocardium or other tissue layer in accordance with the presentinvention;

FIG. 3 is a side view of a delivery assembly for inserting a conduitinto the myocardium or other tissue layer in accordance with the presentinvention;

FIG. 4 is a schematic cross-sectional view of a human heart showing aconduit inserted by a surgical method into a channel created from acoronary artery to the left ventricle in accordance with the presentinvention;

FIG. 5 is an integrated assembly to perforate, dilate, and insert aconduit into a channel in the myocardium or other tissue layer inaccordance with the present invention;

FIG. 6 is a schematic cross-sectional view of a human heart showing aconduit inserted by a surgical method into a channel created from acoronary artery and the left ventricle in accordance with the presentinvention;

FIG. 7 is another embodiment of an integrated assembly to perforate,dilate, and insert a conduit into a channel in the myocardium or othertissue layer in accordance with the present invention;

FIG. 8 is a schematic cross-sectional view of a human heart showing aconduit inserted by a surgical method into a channel created from acoronary artery, both distal and proximal to a blockage, and to the leftventricle in accordance with the present invention;

FIG. 9 is a schematic cross-sectional view of a human heart showing aconduit inserted by a surgical method into a channel created along anextended portion of the myocardium from a coronary artery, both distaland proximal to a blockage, and to the left ventricle in accordance withthe present invention;

FIG. 10 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a surgical method into a channelcreated from a coronary artery to a coronary vein and into the leftventricle in accordance with the present invention;

FIG. 11 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a surgical method into a channelcreated from a coronary vein into both a coronary artery and the leftventricle in accordance with the present invention;

FIG. 12 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a surgical method into a channelcreated from a coronary artery, both distal and proximal to a blockage,through a coronary vein and into the left ventricle in accordance withthe present invention;

FIG. 13 is partial cross-sectional view of a conduit positioned withinthe myocardium in accordance with the present invention;

FIG. 14 is a schematic cross-sectional view of a human heart showing aconduit inserted by a percutaneous method into a channel created fromthe left ventricle to a coronary artery in accordance with the presentinvention;

FIG. 15 is a schematic cross-sectional view of a human heart showing aconduit inserted by a percutaneous method into a channel created from acoronary artery to the left ventricle in accordance with the presentinvention;

FIG. 16 is an integrated assembly to percutaneously perforate, dilate,and insert a conduit into a channel in the myocardium or other tissuelayer in accordance with the present invention;

FIG. 17 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a percutaneous method into a channelcreated from a coronary artery to a coronary vein and into the leftventricle in accordance with the present invention;

FIG. 18 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a percutaneous method into a channelcreated from a coronary artery into a coronary vein distal to thechannel into the left ventricle in accordance with the presentinvention;

FIG. 19 is a schematic cross-sectional view of a portion of the humanheart showing a conduit inserted by a percutaneous method into a channelcreated from a coronary artery, both distal and proximal to a blockage,through a coronary vein and into the left ventricle in accordance withthe present invention;

FIG. 20 is a cross sectional view of an embodiment of the valved conduithaving projections as retaining means in accordance with the presentinvention;

FIG. 21 is a cross sectional view of another embodiment of the valvedconduit having projections as retaining means in accordance with thepresent invention;

FIG. 22 is a cross sectional view of an embodiment of the valved conduithaving a thread as retaining means in accordance with the presentinvention;

FIG. 23 is a cross sectional view of an embodiment of the valved conduithaving a flared end as retaining means in accordance with the presentinvention;

FIG. 24 is a cross sectional view of an embodiment of the valved conduithaving a coating as retaining means in accordance with the presentinvention;

FIG. 25 is a cross sectional view of an embodiment of the valved conduithaving slots as retaining means in accordance with the presentinvention;

FIGS. 26A and 26B are cross sectional views of the myocardium changingthickness along a conduit during systole and diastole, respectively, inaccordance with the present invention;

FIG. 27 is a cross sectional view of an embodiment of the valved conduithaving telescoping sections as adjusting means in accordance with thepresent invention;

FIG. 28 is a cross sectional view of an embodiment of the valved conduithaving telescoping sections as adjusting means in accordance with thepresent invention;

FIG. 29 is a cross sectional view of an embodiment of the valved conduithaving an accordion section as adjusting means in accordance with thepresent invention;

FIG. 30 is a cross sectional view of an embodiment of the valved conduithaving a lateral accordion section as adjusting means in accordance withthe present invention;

FIG. 31 is a cross sectional view of an embodiment of the valved conduithaving a coil as adjusting means in accordance with the presentinvention;

FIG. 32 is a side view of an embodiment of the conduit having a branchconfiguration in accordance with the present invention;

FIG. 33 is a side view of an embodiment of the conduit having a hookconfiguration in accordance with the present invention;

FIG. 34 is a side view of an embodiment of the conduit having a hybridsynthetic/natural configuration in accordance with the presentinvention;

FIG. 35 is a cross sectional view of a vein used as a valve inaccordance with the present invention;

FIG. 36 is a cross sectional view of another embodiment of a vein usedas a valve in accordance with the present invention;

FIG. 37 is a cross sectional view of a valve in accordance with thepresent invention;

FIG. 38A and FIG. 38B are side views of a conduit regulating blood flowduring two phases of the heart cycle in accordance with the presentinvention;

FIG. 39 is a cross sectional view of a valve in a self-maintainedchannel in the myocardium in accordance with the present invention;

FIG. 40 is an isolated front view of the valve in FIG. 39;

FIG. 41 is a cross sectional view of a self-maintained channel in themyocardium in accordance with the present invention; and

FIG. 42 is a cross sectional view of a self-maintained channel in themyocardium in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention generally describes a transmyocardial approachwherein one or more new channels, which are preferably about the size ofa coronary artery, are formed between the left ventricle or otheroxygenated blood source and one or more sites in the arterial vascularsystem of the heart selected for increasing the flow of blood thereto.Preferably, the selected site is in a position distal to one or moreobstructed areas within the coronary circulation. The channel is createdby penetrating completely through the tissue defining the blood source,such as the myocardium which defines the left ventricle, or the vasculartissue, which defines a coronary artery. The channel is maintained in anopen state, by mechanical means or through tissue removal, in order forblood to flow through during the cycle of the heart. The channel isregulated or valved controlling both the direction and/or the quantityof blood flow through the channel between the left ventricle and theselected site in the arterial vascular system of the heart.

The present invention includes several methods for creating andmaintaining a channel in the myocardium for the purposes of connectingan oxygenated blood source to the arterial vascular system of the heart,compromised by a coronary blockage. The inventive methods include bothsurgical and percutaneous approaches. Generally, the surgical approachesinclude direct access to the exterior of the patient's heart via a chestor thoracic approach. The percutaneous approaches include a minimallyinvasive technique using catheters or other devices which are insertedinto the patients' vessels or heart at a remote access site and guidedto the internal blockage site via visualization by instrumentation. Therevascularization is then accomplished remotely.

As defined herein, the term diastole refers to the normal rhythmicalrelaxation of the heart chamber, especially the ventricles, during whichthey fill with blood. The term systole refers to the rhythmiccontraction of the heart, especially the ventricles, during which bloodis driven through the aorta and pulmonary artery after each diastolicperiod. The term distal is generally defined as in the direction of thepatient, or away from a user of a device, or in a downstream directionrelative to a forward flow of blood. In the context of a medical deviceintervention with or through a vascular tissue layer, distal hereinrefers to the interior or the lumen side of the vascular tissue layer orwall. Conversely, proximal generally means away from the patient, ortoward the user, or in an upstream direction relative to a forward flowof blood. In the context of a medical device intervention with orthrough a vascular tissue layer, proximal herein refers to the exterioror outer side of the vascular tissue layer or wall. The term arterialvascular system of the heart includes, but is not limited to, themyocardium and coronary arteries.

Although the present invention is specifically described below withregard to the coronary artery, it should be understood that the presentinvention is not so limited and that the description is applicable toany part of the arterial vascular system of the heart. For example andnot limitation, the description is applicable to the left anteriordescending artery, the circumflex artery, the right coronary artery, andtheir tributaries. The description is also specific with regard to theleft ventricle, but is applicable to other oxygenated blood sources ofthe arterial vascular system such as the left anterior descendingartery, the circumflex artery, the right coronary artery, and theirtributaries proximal to any obstruction or blockage.

A preferred method of the present invention is a surgical approach whichdirectly accesses and exposes the outside of the patient's heart andcoronary vascular system 10 through the chest area using a needleassembly 12 as illustrated in FIGS. 1 and 2. Similar components betweenthe figures herein are denoted by the same reference numerals. Aninitial access port 14 in the myocardium is made by advancing the needleassembly 12 through the myocardium 16 from the exterior side 18 of themyocardium 16 and into the left ventricle 20. Then a second access port22 in the myocardium is made from the interior side 24 of the myocardiumwithin the left ventricle 20 and underneath the coronary artery 26. Theneedle assembly 12 is advanced through the myocardium 16 from the leftventricle 20 and into the coronary artery 26 at a point distal to thelesion or blockage 28.

After the needle assembly 12 has created the second access port 22, aguide wire 30 or other directional means is extended from the distal end32 of the needle assembly into the coronary artery 26. A sufficientlength of the guide wire 30 is advanced into the coronary artery 26 toprevent its premature withdrawal. Optionally, the distal end 34 of theguide wire can contain a balloon 36 or other temporary anchoring meansto prevent premature withdrawal of the guide wire 30 from the coronaryartery. The proximal end 38 of the guide wire extends through the leftventricle 20 to the exterior 18 of the myocardium where it is availablefor manipulation by the surgeon. With the guide wire 30 extending fromthe exterior 18 of the myocardium, through the left ventricle 20 andinto the coronary artery 26, the needle component 40 of the assembly iswithdrawn from both the initial and second access ports.

The method uses the connection made by the second access port 22 betweenthe left ventricle 20 and the coronary artery 26 to create and maintaina channel 42 therebetween. The initial access port 14 is dilated toallow the advancement of a delivery device 44 as illustrated in FIG. 3having a sheath 46 covering a valved conduit 48. The sheath 46 isconfigured to assist the passage of the valved conduit 48 through theinitial access port 14 without snagging the valved conduit 48 ordamaging the myocardium 16. The delivery device 44 is advanced over theguide wire 30, through the initial access port 14, and into the leftventricle 20. The guide wire 30 directs the delivery device 44 to thesecond access port 22. The valved conduit 48 is then removed from thesheath 46 with a pusher rod 74 and the delivery device 44 inserts thevalved conduit 48 into the second access port 22 so that the valvedconduit 48 extends through the myocardium 16 from the left ventricle 20to the coronary artery 26. The conduit 48 keeps the second access port22 dilated and maintains the channel 42 between the left ventricle 20and the coronary artery 26. The end 50 of the conduit preferably extendsinto the left ventricle 20 during the rhythmic contractions of theheart. It is preferred that the valved conduit end 50 extends into theleft ventricle 20 at least during diastole when the myocardium is at theminimal thickness of its cycle. The other end 52 of the conduit can beapproximately flush with the exterior 18 of the myocardium or extendsslightly into the coronary artery 26 during at least during the diastolewhen the myocardium is at the minimal thickness of its cycle.

The remainder of the delivery device 44 is then withdrawn from the leftventricle 20 through the initial access port 14. Either simultaneouswith or subsequent to the withdrawal of the delivery device 44, theballoon 36 at the distal end 34 of the guide wire is deflated (or thetemporary anchor means is retracted) allowing withdrawal of the guidewire 30 from the coronary artery 26 along the valved conduit 48 and fromthe left ventricle 20 through the initial access port 14. The initialaccess port 14 is then sealed with a suture or allowed to seal itselfwithout assistance.

Referring to FIG. 1, another embodiment of the present inventioneffectively anchors the distal end 34 guide wire by initially continuingto advance the guide wire beyond the coronary artery 26. As shown inphantom, the distal end 34A of the guide wire is advanced through theinterior 70 and exiting from the exterior side 72 of the coronaryartery. The distal end 34A is then exposed for anchoring in position.

The needle assembly 12 can be of any shape sufficient to perforate andpenetrate the myocardium 16 while minimizing tissue damage. For example,FIG. 1 shows the needle assembly 12 having a curved shape which canassist in initially penetrating from the exterior side 18 of themyocardium and continuing to penetrate the interior side 24 of themyocardium underneath the coronary artery 26. Other shapes for theneedle assembly 12 are suitable for use in the present invention whichcan penetrate and can depend upon the particular surgical approach to beused. For example and not limitation, FIG. 2 illustrates a straightneedle assembly 12, commonly referred to as a seldinger-type needle. Asuitable diameter for the needle component 40 is about 12 gauge.

FIG. 2 specifically illustrates more details of the needle assembly 12other than an alternate shape. Preferably, the needle assembly 12includes a needle component 40 having at least one lumen 54 extendingsubstantially across length of the needle component. The first lumen 54can be used to allow blood flow therethrough. As the distal end 32 ofthe needle assembly is advanced from the myocardium exterior 18 andenters the left ventricle 20, the blood in the left ventricle 20 willtravel through the lumen 54 and blood 66 will be visually observedexiting the proximal end 62 of the needle assembly. This bleeding“flashback” 66 is especially prominent during the contraction of theleft ventricle 20. As the distal end 32 of the needle assembly isfurther advanced through the left ventricle 20 to contact the myocardiuminterior 24, the bleeding flashback 66 will subside until the distal end32 of the needle assembly completely penetrates the myocardium 16. Theentry of the distal end 32 of the needle assembly into the coronaryartery 26 will be evidenced by resumption of the bleeding flashback 66through the proximal end 62 of the needle component or some otheraccessing feature. The first lumen 54 is also used to retractably carrythe guide wire 30 therethrough.

Optionally, the assembly 12 can include a second lumen 56 which alsoextends substantially across the length of the needle component 40. Oneend 58A of the second lumen is located at the distal end 32 of theneedle component. Alternately, the end 58B of the second lumen islocated at some predetermined distance from the distal end 32 of theneedle component. The other end 60 of the lumen is located near theproximal end 62 of the needle component. As the distal end 32 of theneedle assembly is advanced from the myocardium exterior 18 and entersthe left ventricle 20, the blood in the left ventricle 20 will travelfrom one end 58A or 58B of the second lumen to the other end 60 andblood 66 will be visually observed exiting the proximal end 62 of theneedle assembly.

The lumen 54 or second lumen 56 and its ends 60 and 58A or 58B act asmarker ports which provide evidence when the distal end 32 of the needleassembly is first in the left ventricle 20 and subsequently in thecoronary artery 26. Other means for marking the position of the distalend 32 of the needle assembly are suitable for use with the presentinvention. For example and not limitation, the depth of the penetrationthrough the myocardium to form the initial and second access ports 14and 22 can be estimated by conventional diagnostic imaging and/or byreading one or more depth markers 68 placed in predetermined positionsalong the length of the needle assembly 12.

The needle assembly 12 provides for perforating the myocardium 16 tocreate and access port. The assembly 12 also provides for dilating theaccess port and for ensuring the position of the assembly has beenadvanced into the left ventricle 20 and/or coronary artery 26.

Another inventive method is a surgical approach which gains access tothe exterior of the patient's heart illustrated in FIG. 4 throughconventional cardiac surgical methods. Using the needle assembly 12 aspreviously described in FIG. 2, an initial access port 76 is made in thecoronary artery 26 distal to the point of the obstruction 28. The needleassembly 12 is advanced into and through the coronary artery 26 tocontact the exterior 18 of the myocardium underneath the coronary artery26. The needle assembly 12 is further advanced to penetrate themyocardium 16 and make an access port 78 in the myocardium whileeventually entering the left ventricle 20. The needle assembly 14extends into the left ventricle 20 to the extent that flashback bleeding66 is observed to assure the myocardium 16 has been completelypenetrated.

After the needle assembly 12 has created the second access port 22, aguide wire 30 or other directional means is extended from the distal end32 of the needle assembly into the left ventricle 20. A sufficientlength of the guide wire 30 is advanced into the left ventricle 20 toprevent its premature withdrawal. Optionally, the distal end 34 of theguide wire can contain an inflatable balloon 36 or other temporaryanchoring means to prevent premature withdrawal of the guide wire 30from the left ventricle 20. With the guide wire 30 extending from theleft ventricle 20 to the exterior 18 of the myocardium underneath thecoronary artery 26, through the interior 70 of the coronary artery andto the exterior 72 of the coronary artery, the needle component 40 ofthe assembly is withdrawn from both the access ports 78, 76.

In another embodiment of this surgical approach wherein the initialaccess port 76 is created in the exterior of the coronary artery 26, itmay be desirable to offset the alignment of the initial access portshown as 76A from the myocardium access port 78. This can beaccomplished in several ways such as through simple angling of theneedle assembly 12 while creating the access ports or using a needleassembly 12 which is curved or has an offset in its configuration. Theeventual closing of the initial access port 76 may cause trauma to thevascular tissue in that area. Providing an offset in the alignment ofthe access ports 76A, 78 avoids the initial access port area from beingdirectly over or along the path of the blood flow path from the insertedvalved conduit 48.

Similar to what has been discussed before, the access port 78 in themyocardium is dilated to accommodate the delivery of a valved conduit 48therein. Inserting the valved conduit 48 into the access port 78 createsand maintains by mechanical means a channel 42 through the myocardiumfrom the left ventricle 20 to the coronary artery 26. The delivery ofthe valved conduit 48 can be effectuated by inserting a guide wire 30,withdrawing the needle assembly 12, directing a delivery assembly 44 asseen in FIG. 3 containing the valved conduit 48 over the guide wire 30through the initial access port 76 to the access port 78, dilating theaccess port 78, inserting the valved conduit 48 into the access port 78,and withdrawing the delivery assembly 44 and guide wire 30 from the leftventricle 20 and coronary artery 26. Subsequently, the initial accessport 76 on the exterior 72 of the coronary artery is closed by stitches,staples, or other closure means.

An alternate embodiment of the present invention employs a needleassembly and delivery assembly which are integrated so that the guidewire is eliminated. The integrated assembly provides sufficient dilationof the respective access ports to deliver the valved conduit therein.For example, as illustrated in FIG. 5, an integrated assembly 80includes a perforating distal end 82 with a series of gradations orsteps 84 for gradually dilating the respective access port as theintegrated assembly 80 is further advanced. The steps 84 can bepre-formed or result from a retractable telescoping of the body 86 ofthe integrated assembly which can gradually vary its diameter. Thevalved conduit 48 is then removed from the body 86 with a pusher rod 88and the integrated assembly 80 inserts the valved conduit 48 into theaccess port 78 so that the valved conduit 48 extends through themyocardium 16 from the left ventricle 20 to the coronary artery 26. Theconduit 48 keeps the access port 78 dilated and maintains the channel 42between the left ventricle 20 and the coronary artery 26.

Still another inventive method is a surgical approach which gains accessto the exterior of the patient's heart and coronary vascular system 10illustrated in FIG. 6 through conventional cardiac surgical methods.Using a first integrated needle/delivery assembly 90, an access port 92is created through the myocardium 16 from the exterior side 18 into theleft ventricle 20. Similar to the previous description herein, thedistal end 98 of the integrated needle assembly perforates themyocardium and the myocardium access port 92 is dilated to accommodatethe delivery of one end 96 of the valved conduit 94 which is advancedinto the myocardium access port 92. Inserting the end 96 of the valvedconduit into the myocardium access port 92 creates and maintains achannel through the myocardium 16 from the left ventricle 20 into oneend 96 of the valved conduit.

Using a second needle/delivery assembly 100, an artery access port 102is made in the exterior side 72 of the coronary artery. With surgicalaccess to the artery access point 102, the second integratedneedle/assembly 100 can immediately dilate the artery access port 102and insert the other end 104 of the valved conduit after the integratedneedle/delivery 100 perforates the coronary artery 26. Inserting theother end 104 of the valved conduit into the artery access port 102creates and maintains a channel 42 from the left ventricle 20 into oneend 96 of the valved conduit, out the other end 104 of the valvedconduit, and into the coronary artery 26.

The first needle/delivery assembly 90 is more specifically illustratedin FIG. 7 which includes a body 106 made of a flexible material. Thebody 106 is perforated along its longitudinal axis to form seams 108.The valved conduit 94 extends along the longitudinal axis of the body106 with the end 96 of the valved conduit positioned near the distal end98 of the assembly and the other end 104 of the valved conduit exitingfrom the proximal end 110 of the assembly. Once the assembly 90 hasperforated and dilated the myocardium access port 92, gripping the otherend 104 of the valved conduit exiting from the assembly 90 can behelpful in either advancing the end 96 of the valved conduit into themyocardium access port 92 or holding the end 96 of the valved conduitwithin the myocardium access port 92 as the remainder of the assembly 90is withdrawn. To ease the withdrawal of the assembly 90 from themyocardium access port 92, the perforations are broken apart to splitthe seams 108 and the longitudinal sections 112 and 114 of the body 106are peeled away leaving the end 96 of the valved conduit in themyocardium access port 92.

In one alternate embodiment of the type of valved conduit that can beused with this surgical approach, the valved conduit 94 can have twoseparate conduit sections wherein a first conduit section 118 isinserted in the myocardium access port 92 and a second conduit section119 is inserted in the artery access port 102. Subsequently, the twosections are connected together to form a continuous channel for theblood flow from the left ventricle 20 to the coronary artery 26. Thevalve 116 can be integrally positioned in either the first or secondconduit section. Or, the valve 116 can be a separate piece from the twoconduit sections wherein each conduit section connects to opposite sidesof the valve.

In another embodiment of this surgical approach, delivery of either end96 or 104, or both ends, of the valved conduit 94 can be effectuated byinserting a guide wire through a needle assembly as illustrated in FIG.2 into the left ventricle 20, withdrawing the needle assembly, directinga delivery assembly as illustrated in FIG. 3 containing the valvedconduit 94 over the guide wire to the myocardium access port 92,dilating the myocardium access port 92, inserting one end 96 of thevalved conduit into the myocardium access port 92, and withdrawing thedelivery assembly and guide wire from the left ventricle 20.

A further inventive method is a surgical approach which directlyaccesses and exposes the outside of the patient's heart and coronaryvascular system illustrated in FIG. 8. Using a first needle/deliveryassembly 120 of similar design to the one illustrated in FIG. 7, amyocardium access port 122 is made in the myocardium 16 from theexterior side 18 into the left ventricle 20. The myocardium access port122 is dilated to accommodate the delivery of a first input end 124 of aY-shaped, multi-branched valved conduit 126 therein. Inserting the firstinput end 124 of the valved conduit into the myocardium access port 122creates and maintains a channel 148 through the myocardium 16 from theleft ventricle 20 into a first input end 124 of the conduit.

Using a second needle/delivery assembly 128, a distal artery access port130 is made in the exterior side 72 of the coronary artery at a pointdistal to the lesion or blockage 28. With surgical access to the distalartery access port 130, the second assembly 128 can immediately dilatethe distal artery access port 130 and insert an output end 132 of themulti-branched conduit after the second assembly 128 perforates thecoronary artery 26.

Using a third needle/delivery assembly 134, a proximal artery accessport 136 is made in the exterior side 72 of the coronary artery at apoint proximal to the obstruction or blockage 28. With the surgicalaccess to the proximal artery access point 136, the third assembly 134can immediately dilate the proximal artery access port 136 and inserts asecond input end 138 of the multi-branched conduit after the thirdassembly 134 perforates the coronary artery 26. Inserting the firstinput end 124 of the multi-branched conduit into the myocardium accessport 122 and the second input end 138 of the multi-branched conduit intoproximal artery access port 136 creates and maintains two channels 140and 142 from two different blood sources, namely the left ventricle 20and the coronary artery 26 proximal to the blockage 28, into the outputend 132 of the multi-branched conduit and into the coronary arterydistal to the blockage 28.

Preferably, a multi-branch, valved conduit 126 is used having at leasttwo branches 140 and 142 with valving means 144 located in branch 140.With access afforded by this surgical approach, the two input ends 124and 138 and output end 132 of the valved conduit each can be insertedsimilar to the previous description of FIGS. 6 and 7 without theassistance of remote guidance which avoids using a guide wire or thelike through the interior of the conduit.

In an alternate embodiment of this surgical approach, each branch 140and 142 of the conduit can initially be a separate component which canbe connected together after the two input ends and output end have beeninserted into the myocardium and the coronary artery proximal and distalto the blockage. The valving means 144 minimizing blood flow into theleft ventricle is located in the branch 140 leading from the myocardium16 between the first input end 124 and the connection to the secondinput end 138 and the output end 132. Alternately, the valving means 144can be located near the distal artery port 130 as shown in phantom as148. Optionally, a second valving means 146 for minimizing blood flowinto the proximal coronary artery can be located in branch 142 leadingfrom the proximal coronary artery between the second input end 138 andthe connection between the first input end 124 and the output end 132. Asecond valving means 146 is particular useful if there is a valvingmeans located near the distal artery port 130.

It should be understood that portions of different approaches can becombined. For example, a portion of the surgical approach described inFIG. 8 can be used to connect the proximal and distal coronary artery 26with a channel like branch 142 external to the heart. Instead ofproviding another external channel like branch 140 to connect the leftventricle 20 with the distal coronary artery 26, a surgical approach asdescribed in FIG. 1 or 4 can provide an internal channel like 42 (FIG. 1or 4) positioned through the myocardium 20. As a result, blood flow fromthe left ventricle 20 arrives to the distal coronary 26 by an internalchannel like 42 and from the proximal coronary artery through externalchannel like 142.

FIG. 9 illustrates another embodiment of a surgical approach whichdirectly accesses and exposes the outside of the patient's heart andcoronary vascular system 10 for the placement of a valved conduit 150through an extended portion along, or at an obtuse angle through, themyocardium 16 rather than taking the shortest path roughlyperpendicularly through the myocardium. Using a first needle/deliveryassembly 154, proximal artery access port 156 is made on the exteriorside 72 of the coronary artery. The assembly 154 is advanced through theinterior 70 of the coronary artery and along the myocardium beforeeventually creating an access port 160 to the left ventricle 20 throughthe myocardium 16. The proximal artery access port 156 and leftventricle access port 160 are dilated to accommodate the delivery of onebranch 162 of the valved conduit 150 so that the valved conduit 150 ispositioned at least partially along the myocardium and is preferablysubjected to the movement created by the rhythmic contractions of thebeating heart.

Using a second needle/delivery assembly 166, a distal artery access port168 is created through the coronary artery 26 at a point distal to thelesion or blockage 28 into the exterior side 18 of the myocardium toconnect with or near the left ventricle access port 160. The secondassembly 166 can immediately dilate the distal artery access port 168and insert the other branch 164 of the valved conduit into the coronaryartery 26. As a result, the valved conduit 150 has two branches 162, 164which traverse the myocardium 16 at an obtuse angle. The valved conduit150 exhibits a substantially greater length compared to perpendicularlytraversing the myocardium between the left ventricle 20 and coronaryartery 26.

Although the valved conduit 150 can have a solid, rigid design, it ispreferred in this embodiment to advantageously use the movement createdby the rhythmic contractions of the beating heart to provide theregulation of the blood flow from the left ventricle 20 to the coronaryartery 26 distal to the blockage 28. Accordingly, it is preferred that asubstantial length the valved conduit 150 be made of a flexible materialwhich allows the walls 152 of the valved conduit to flex with therhythmic contractions of the beating heart and assist in the regulationof blood flow. The flexing of the conduit walls 152 can occur in severalways such as compression of its diameter or the lateral collapse of theconduit walls 152 upon themselves. It may be desirable to providerigidity to the conduit walls 152 in the area of the valve 158 locatednear the access port 160 to preserve the integrity of the blood flowregulation by the conduit. It should be noted that the branches do nothave to be connected and terminate at one access port 160. A secondaccess port to the left ventricle is also suitable, so that each branch162, 164 has a separate access port to the left ventricle 20.

Alternately, it is suitable to remove the valve 158 as a distinctcomponent of the conduit by allowing the conduit walls 152 to flex bycollapsing opposing walls against each other to provide the appropriatedegree of closure during diastole. It may also be desirable to providefor regulating blood through both branches by locating the valve 158only in branch 162. Examples of the proper alignment of the valvedconduit 150 traversing the myocardium 16 are described in more detailbelow.

Other means of positioning the valved conduit 150 along a more extensivepath between the left ventricle 20 and coronary artery 26 are suitablefor use in the present invention. For example and not limitation, thedirect access to the exterior of the heart 10 allows a trough to beexcised between the left ventricle access port 160 and the distal arteryaccess port 168. The left ventricle access port 160 can be created atone end of the trough and the distal artery access port 168 at the otherend of the trough. One end of the valved conduit 150 is then positionedinto the left ventricle and extends within the trough to the other endof the valved conduit which is inserted into coronary artery 26 aspreviously described therein.

Although the position of the valved conduit 150 is specificallyillustrated as traversing the myocardium along an extended path orobtuse angle, it should be noted that the present invention is not solimited. The valved conduit 150 can be positioned partially or whollywithin the myocardium including other tissue layers enveloping the hearti.e. pericardium, epicardium, endocardium, etc., or external to theheart and vascular system, or in a combination thereof.

Another embodiment of the surgical approach using the valved conduit atleast partially positioned within the myocardium is to utilize a valvedconduit with only one branch similar to the methods illustrated in FIGS.1, 4 and 6. Optionally, other branches are added to the valved conduit150 of FIG. 9 to connect to other sources of oxygenated blood, namelyanother coronary artery, or to deliver the oxygenated blood to multipleischemic areas. Each additional branch can be positioned across themyocardium along an extended path or obtuse angle as described above orin a perpendicular direction across the myocardium.

FIG. 10 illustrates another embodiment of a surgical approach whichdirectly accesses and exposes the outside of the patient's heart andcoronary vascular system 10 for the placement of a valved conduit 180across the myocardium 16. A needle/delivery assembly 182 creates aninitial access port 184 in the exterior side 72 of the coronary arterydistal to the blockage 28. The assembly 182 is advanced through theinterior 70 of the coronary artery to create an access port 190 throughthe vascular wall 186 of an adjacent coronary vein 188. The assembly 182is then advanced through the coronary vein 188 to create an access port192 in the exterior side 18 of the myocardium and completely through themyocardium 16 into the left ventricle 20. The valved conduit 180 is theninserted into and through the myocardium 16 creating a channel 42directly from the left ventricle 20 to the coronary vein 188. The bloodflow into the coronary vein 188 is limited to a particular area orsection 170 by inserting plugs 194 within the coronary vein proximal anddistal to the access ports 190, 192. The plugs 194 can be moved intotheir respective positions by insertion through the access ports 184,190. Another technique for inserting the plugs 194 is to perforate,dilate, and insert the plugs 194 directly through the exterior side ofthe coronary vein 188 near the area the plugs 194 are desired. Devicesor techniques other than plugs 194 can be used to isolate a section ofthe coronary vein 188 such as by using a suture around the vein in aposition at least proximal to the access ports 190, 192 to close offblood flow to the section.

A second conduit 196 is inserted into the access port 190 to maintain asecond channel 198 between the coronary artery 26 and the coronary vein188. As a result, blood flows during systole from the left ventricle 20into the coronary vein 188 and subsequently into the coronary artery 26distal to the blockage 28. The coronary vein 188 can provide a temporaryreservoir of blood. The valved conduit 180 minimizes backflow of bloodfrom the coronary vein and artery during diastole. Upon withdrawal ofthe assembly 182, the initial access port 184 is closed.

As illustrated, the conduit 180 can optionally include a reservoirconnected to it for temporarily storing blood. The reservoir may be aseparate container like the section 170 of the coronary vein 188 that isconnected to the conduit 180 or a container that is integrally formedwith the surface of the conduit. The reservoir can also be effectivelyformed from a material which has the ability to expand and contract sothat it becomes a reservoir during certain periods of the heart cycle.

The assembly 182 can be elongated to initially contain both the valvedconduit 180 and the second conduit 196 so that each may be respectivelypositioned without withdrawing the needle assembly from the initialaccess port 184. Other alternates are available, such as withdrawing theneedle assembly 182 to reload with the conduit not first placed inposition. Or, temporarily dilating the access port 184 with anotherdevice so that a second needle/delivery assembly can be inserted throughthe same access port.

Although there is only one valved conduit 180 and it is positionedcompletely through the myocardium 16, the present invention includesseveral other options for regulating blood flow. For example, one optionis to position the valved conduit 180 between the coronary artery 26 andcoronary vein 188 and position the second conduit 196 without a valvethrough the myocardium between the left ventricle 20 and the coronaryvein 188. This arrangement creates a reservoir of blood within thecoronary vein 188 which may allow for blood flow into the coronaryartery 26 during diastole.

Another option positions the valved conduit 180 and second conduit 196as illustrated in FIG. 10. However, a valve shown in phantom as 180A isadded to the second conduit 196. As a result, the coronary vein 188provides a reservoir of blood in section 170 which augments blood flowinto the coronary artery 26 during diastole.

Another embodiment of this surgical approach wherein the channel betweenthe left ventricle and coronary artery is transvascular andtransmyocardial as illustrated in FIG. 11. An initial access port 184Ais created in the top exterior of the coronary vein 188 instead of thecoronary artery 26. The assembly 182 is advanced to create the accessport 190 into the coronary artery 26, to insert the second conduit 196and is then withdrawn. The assembly is also advanced from the initialaccess port 184A to create the access port 192 into the myocardium 16,insert the valved conduit 180 and is then withdrawn.

Alternately, the initial access port 184A is created to advance theassembly 182 and create an access port from the coronary vein 188 toeither the left ventricle 20 through the myocardium 16 or to thecoronary artery 26, but not both. Another initial access port 184B iscreated with the same or another assembly to complete the remainingaccess port. For example, access port 192 is made through the myocardiumand the alternate access port 184B is used to make alternative accessport 190B into the coronary artery 26. As a result, the alignment of theaccess ports 190B, 192 is offset from one another.

Although a valved conduit 180 is specifically illustrated in FIGS. 10and 11, the coronary vein 188 itself can be used to regulate the flow ofblood from the left ventricle 20 into the coronary artery 26. In thisembodiment, the conduits 180 and 196 need not be valved, but simplymaintain the respective channels. As discussed in more detail below, thenatural valving function of vascular tissue in the isolated section ofthe coronary vein 188 can be advantageously used to regulate the flow ofblood.

The present invention includes still another surgical approach whereintransvascular and transmyocardial channels between the left ventricleand coronary artery extend to more than one blood source as illustratedin FIG. 12. An additional initial access port 174A is created in the topexterior of the coronary vein 188 at a position which is proximal to theblockage 28 in the adjacent coronary artery 26. The assembly 182 isadvanced through the interior of the coronary vein 188 to create anadditional access port 172 for a third channel 178 through the exteriorwall 72 of an adjacent coronary artery. A third conduit 176 is insertedinto the additional second access port 172 to maintain the channel 178.One of the plugs 194 is inserted into the coronary vein 188 in aproximal position to the additional initial access port 174A.

Alternately, the additional initial access port 174B is created in thetop exterior of the coronary artery proximal to the blockage 28. Theassembly 182 is then advanced through the interior of the coronaryartery to create the third channel 178 through the exterior wall 186 ofan adjacent coronary vein.

Another method of the present invention is a surgical approach whichdirectly accesses and exposes the outside of the patient's heart andcoronary vascular system 10 through the chest area as illustrated inFIG. 13. As described herein, a needle delivery assembly can be used toperforate and dilate an access port 200 in the exterior side 18 of themyocardium so as to insert a valved conduit 204, preferably having ahorizontal branch 208 to form a T-shape, into the left ventricle 20. Thevalved conduit 204 is positioned so that the branch 208 lies within themyocardium and the end 210 of the valved conduit extends within the leftventricle 20. The branch 208 is positioned to lie parallel to themyocardium 16. The valve 212 in the conduit is preferably positionednear the end 210. After insertion of the valved conduit 204, theexterior side 18 of the myocardium is closed by suturing or othersuitable closure means.

Alternately, an incision can be made along a suitable course in theexterior side 18 of the myocardium such as along the phrenic nerve intothe vascular area of myocardium 16 above the left ventricle 20 in frontof the coronary artery. The incision is deepened almost to the interiorside 24 of the myocardium or the endocardium 202. Optionally, a smallcavity 206 can be created to assist in the placement of the conduit 204.As previously described, a needle assembly is then used to perforatethrough the endocardium 202 or remaining myocardium below the incision200, to the left ventricle 20.

An example of suitable dimensions for the preferred T-shaped valvedconduit 204 is about a 4 mm diameter with a vertical branch 214 of about15 mm and the horizontal branch 208 of about 20 mm long. The horizontalbranch 208 is provided to divert blood flow into a direction parallel tothe myocardium 16 layer. Other designs for the valved conduit 204 aresuitable for use in the present invention. For example and notlimitation, the valved conduit 204 can be a straight stem or have a twohorizontal branches in a cross shape. The valved conduit 204 can be madeof a porous material that allows blood flow to emanate from the entirelength, or selected portions, of the vertical branch 214 and/orhorizontal branch 208.

Another preferred method of the present invention is a percutaneousapproach which generally introduces a catheter or otherguidance/delivery device into the blood source such as the leftventricle. A catheter 220 is placed into the circulatory system 10 at aremote access site such as the femoral artery and advanced through theaortic valve into the left ventricle 20 as illustrated in FIG. 14. Thecatheter 220 then is directed to the interior side 24 of the myocardium16 underneath the coronary artery 26 where a penetrating or perforatingneedle 222 is delivered and advanced from the left ventricle 20 throughthe myocardium 16 into the coronary artery 26 to create an access port224 therethrough.

Once the catheter 222 has been guided to the desired location, theperforating needle 222 is exchanged for a valved conduit 226 which isdelivered to the access port 224 and inserted into the myocardium 16. Asdescribed above, the valved conduit 226 extends completely through themyocardium 16 to create and maintain a channel 42 between the leftvertical 20 and the coronary artery 26 distal to the blockage 28.

There are several conventional techniques for locating the position of acatheter 222 in various places in the human body. For example and notlimitation, the locating means can be an ultrasound system, magneticresonance imaging, computer aided tomography or an echocardiograph. Afluid or medium such as a dye can be introduced by conventional meansinto the left ventricle 20 that allows its identification by a scanninginstrument and provides a background to identify the location of theguided catheter 222 in relation to the coronary artery 26 and the leftventricle 20.

A suitable inventive method using the percutaneous approach isillustrated in FIGS. 15 and 16. A catheter 228 and guide wire 238 areinserted into the coronary artery 26 from a remote access site such asalong the femoral artery. The guide wire 238 is used to cross theblockage 28 and then the catheter 228 is inserted over the guide wireand advanced past the blockage. The catheter 228 includes a body 230having a distal end 232 and proximal end 234 with a window 236. A guidewire 238 assists in guiding the catheter 228 into the desired positionand exchanging a perforating needle 244 and a valved conduit asdiscussed above. The window 236 is rotated for proper orientation sothat the window 236 faces the tissue layer of the coronary artery 26against the exterior side 18 of the myocardium wherein an access port248 is to be created. Optionally, the body 230 includes a balloon 240which can retractably expand against the inner tissue wall of thecoronary artery 26 to hold the window 236 in its proper orientation.

The body 230 includes a ramp 242 which directs the perforating needle244 on a wire into the tissue layer to create the access port 248.Preferably, the wire 238 has a hole in its center to provide for backbleeding as means of evidencing the position of the needle 244.Alternately, the scanning instrument can determine the position of theneedle 244 advancement. Subsequently, the ramp 242 directs the insertionof the valved conduit 250 into the created access port.

Another embodiment of the present invention combines portions ofdifferent percutaneous approaches. As described in FIG. 15, a guide wire238 is inserted into the coronary artery 26 from a remote access sitesuch as along the femoral artery. The guide wire 238 is used to crossthe blockage 28 and is advanced into the left ventricle 20. Using thepath described in FIG. 14, a guide wire is advanced from the same accesssite into the left ventricle and is used to snare the guide wire 238advanced from the coronary artery and retrieve the guide wire 238 backto the remote access site. As a result, the guide wire 238 completes acircuit from the remote access site through the coronary artery, acrossthe myocardium, to the left ventricle and back to the remote accesssite. One or more devices can then be advanced through the leftventricle to the interior side of the myocardium without crossing theblockage in the coronary artery.

Another inventive method using the percutaneous approach which advancesa catheter 260 into the coronary artery 26 from a remote access sitesuch as along the femoral artery is illustrated in FIG. 17. Once theposition of the catheter 260 is determined within the coronary artery26, a penetrating wire 262 is advanced from the catheter to go from thecoronary artery and penetrate into an adjacent coronary vein 264. Anexcess amount of the penetrating wire 262 is advanced into the coronaryvein 264 to assist in retaining the penetrating wire within the coronaryvein as the catheter is similarly advanced from the coronary artery 26into the coronary vein 264. The position of the catheter 260 is thendetermined in the coronary vein 264 relative to the left ventricle 20.The catheter 260 is directed to orient the perforating wire 262 towardsthe myocardium 16 underneath the coronary vein 264 and to the leftventricle 20.

The perforating wire 262 creates an initial access port 268 through thevascular wall 272 of the adjacent coronary vein 264 and a second accessport 270 in the exterior side 18 of the myocardium and completelythrough the myocardium 16 into the left ventricle 20. A valved conduit266 is then inserted into and through the myocardium 16 creating achannel 42 directly from the left ventricle 20 to the coronary vein 264.The blood flow into the coronary vein 264 is limited to a particulararea or section 286 by inserting plugs 274 within the coronary vein onboth sides of the initial and second access ports 268, 270. The plugs274 can be moved into their respective positions by insertion throughthe initial access port 268.

A second conduit 276 is inserted into the initial access port 268 tomaintain a second channel 278 between the coronary artery 26 and thecoronary vein 264. As a result, blood flows during systole from the leftventricle 20 into the coronary vein 264 and subsequently into thecoronary artery 26 distal to the blockage 28. The coronary vein 264 canprovide a temporary reservoir of blood. The valved conduit 266 minimizesbackflow of blood from the coronary vein 264 and artery 26 into the leftventricle 20 during diastole.

Another embodiment of this method is illustrated in FIG. 18. The initialaccess port 268 is offset in its alignment with the second access port270A. The catheter 260 is guided to a location either a distance furtherdistal or proximal to the initial access port 268 before the secondaccess port 270A is created. FIG. 18 specifically illustrates a distalposition.

The present invention includes still another percutaneous approachwherein transvascular and transmyocardial channels between the leftventricle and coronary artery extend to more than one blood source asillustrated in FIG. 19. An additional access port 280 is created betweenthe coronary artery and the adjacent vein 264 proximal to the blockage28 in the adjacent coronary artery 26. The catheter 260 is advancedthrough the interior of the coronary vein 264 to create the access ports268 and 270. A third conduit 282 is inserted into the additional accessport 280 to maintain the third channel 284. One of the plugs 274 isinserted into the coronary vein 264 in a proximal position to theadditional access port 280.

It should be understood that the present invention provides forcombining portions of different surgical approaches, differentpercutaneous approaches, or a combination of surgical and percutaneousapproaches in one method. For example, a surgical approach can use acatheter in a method similar to that described with reference to FIGS.14-19. After gaining access to the exterior of the patient's heart andcoronary vascular system, the same access area is used to guide thecatheter to the coronary vascular system at a location which issignificantly closer to the heart.

The present invention provides alternate methods of creating the accessports for the surgical and percutaneous approaches described above.Instead of dilating the access ports, a section of tissue can be removedto provide the channel through the myocardium or the vascular tissue.The diameter of the tissue section to be removed is preferably aboutequivalent to or larger than the diameter of the valved conduit to beinserted.

For example and not limitation, a section of tissue can be removed bymechanical means such as by positioning a rotary drill head or punch atthe distal end 32 of the needle assembly in FIG. 2 or the distal end ofthe delivery device 44 in FIG. 3. As the result, the dilation of theaccess port is partially or completely obviated.

Another suitable means for removing tissue is laser energy which iscommonly used in transmyocardial revascularization (TMR) techniques withadjustments to make a larger diameter channel than is conventionallyused in TMR. A laser can be used with either the surgical orpercutaneous approaches described herein. The surgical approachesprovide adequate space to align the laser from a position external tothe heart and vascular system or the laser can be introduced into theleft ventricle or coronary system and create a channel from the insideextending outward. A laser fiber can be carried by a guided catheter asdescribed in the methods above.

The tissue removal means of the present invention provides channelswhich are self-maintaining. Channels created by the removal of tissuecan avoid the use of a conduit to keep or maintain the channel open. Asdefined herein, the term self-maintained channel is a passageway throughtissue which is open for blood flow from an oxygenated blood source to aselected site during at least a portion of the heart cycle, preferablyduring systole. With a self-maintaining channel, the regulation of bloodis controlled by inserting only a valve, no conduit, into the channel.Or, the self-maintained channel can regulate the flow of blood naturallyby orienting the self-maintained channel through the myocardium asdescribed herein.

The conduits and valves of the present invention are made of naturalvascular tissue or synthetic materials or a combination of both. Thesynthetic materials are bio-compatible and include metals, alloys andplastics containing one or more polymers. The conventional surgicalpolymers are suitable plastics. Metals or alloys which are not inthemselves bio-compatible can be coated with a bio-compatible metal orplastic. Preferably, the conduit material is non-porous to blood.However, it is suitable to use material porous to blood and stillprovide blood flow completely through the length of the conduit.

A preferred synthetic conduit 400 is illustrated in FIG. 20 having anelongated body 402 with a cylindrical or tubular shape and a wall 404having an exterior surface 406 and an interior surface 408. The wall 404defines an interior space 410. The body 402 includes an inlet end 412for receiving blood from the left ventricle or other oxygenated bloodsource and an outlet end 414 for delivering the oxygenated blood to aselected site such as a coronary artery or vein.

The preferred shape of the cross-section of the body 402 along itslongitudinal axis 416 is circular. Other cross-sectional shapes aresuitable for use by the present invention such as, for example and notlimitation, triangular, rectangular, square, elliptical, oval, and othergeometric or free-form shapes. The cross-sectional size is illustratedas uniform across the length of the body 402. However, thecross-sectional size can vary along the length of the body 402, or taperor flare the body 402 near the ends 412 and 414.

The diameter of the conduit 400 is preferably not expandable and isinserted into the channel 42 as a predetermined size without the need toexpand the diameter of the body 402. The body 402 resists compressiveforces placed on it by the myocardium during the heart cycle to maintainthe channel 42 in the open position. However, the present invention alsoprovides for using conduits with a diameter which is expandable afterinsertion into the myocardium.

Preferably, the length of the conduit 400 is sized to be longer than themaximum width the myocardium achieves during the heart cycle. Theconduit 400 extends beyond the exterior side 18 and interior side 24defining the myocardium and slightly into the left ventricle 20 andcoronary artery 26. It is suitable to provide the length of the conduit400 so that one end is approximately flush with the interior side 24and/or exterior side 18 of the myocardium.

The conduit 400 includes projections 418 integrally formed with the body402 near the inlet end 412 and outlet 414 means for retaining theconduit in position once it has been inserted within the myocardium 16or other tissue layer. The projections 418 can have an end 420 which isbarbed or otherwise shaped for slightly penetrating, embedding, orabutting the myocardium 16 in the area surrounding the ends 412 and 414.The connection between the body 402 and the projections 418 includes aspring bias which allows the projections 418 to fold relatively flatagainst the exterior surface 406 of the body while the conduit 400 isbeing inserted into the channel 42 through the myocardium 16 or tissuelayer. The projections 418 then relax to their outwardly extendedposition once the ends 412, 414 of the conduit extend into the leftventricle 20 and coronary artery 26 and are clear of the channel 42. Forexample, the spring bias can be supplied by conventional memory orsuperelastic materials.

Preferably, the synthetic conduit 400 includes a valve 422 having flaps424 which open to allow blood flow in one direction from the leftventricle 20 to the coronary artery 26 and close to minimize thebackflow of blood in the reverse direction. The closure of the flaps 424need not completely seal the interior space 410. The valve 422 can besupported by a ring 426 inserted within the interior space 410 so as toabut the interior surface 408 as a component separate from the body 402.Alternately, the valve 422 can be integrally formed with the wall 404.

Other examples of retaining means are provided by the present invention.For example and not limitation, FIG. 21 illustrates projections 430which are initially retracted into the interior space 410 through slots432 in the wall 404. The connection between the body 402 and theprojections 430 includes a spring bias which allows the projections 430to retract into the interior space 410 of the body while the conduit 400is being inserted into the channel 42 through the myocardium 16 ortissue layer. The projections 430 then released to their outwardlyextended position once the conduit 400 is in the desired position. Thisembodiment also illustrates that the projections 430 slightly penetratethe face 434 of the channel 42 rather the area of the myocardiumsurrounding the channel.

Another example of the retaining means provided by the present inventioninclude forming a screw thread 436 on the exterior surface 406 of thebody as illustrated in FIG. 22. The thread 436 is of sufficient size andquantity to hold the conduit 400 in the desired position by biting intothe face 434 of the channel. The thread 436 can extend over one or moresections of the exterior surface 406. The thread 436 need not becontinuous and can be positioned anywhere along the length of theexterior surface 406.

Other examples of the retaining means provided by the present inventionincludes expanding one or both ends of the conduit 400 to a diametergreater than the channel 42. FIG. 23 illustrates the inlet end 412 beingflared 438 so that its diameter is greater than the diameter of thechannel 42. The flared end 438 extends beyond the myocardium 16 layer.The end 438 can be flared prior to or after insertion of the conduit 400into desired position. FIG. 24 illustrates the inlet end 412 beingeffectively expanded by a coating 440 applied to the exterior surface406 of the conduit near the end. The coating 440 expands after insertion440A to hold the conduit 400 in the desired position. There are severalknown plastics or foams which exhibit predictable expansion propertieswhich are suitable material for use as the coating 440.

In similar embodiments, an adherence between the exterior surface 406 ofthe conduit and the face of the myocardium along the channel can bepromoted to retain the conduit in the desired position. For example, atleast a portion of the length of the conduit 400 can be coated on theexterior surface 406 with a bio-compatible adhesive which assists theadherence with the face of the myocardium. Another example is to abradethe exterior surface 406 of the conduit.

FIG. 25 illustrates that the retaining or anchoring means can be locatedanywhere along the length of the body 482 of the conduit 480 such as themiddle section 484. Another type of anchoring means is also illustratedin the form of elongated slots 486. By having comparable sizes in thediameters of the conduit 480 and the channel, the face of the myocardiumalong the channel may embed into the areas of the slots 486 to retainthe conduit in the desired position.

The retaining means can also be useful in sizing the length of a conduitimmediately after insertion through the myocardium. For example, usingthe surgical approach described in reference to FIG. 4, a conduit havinga length significantly longer that the myocardium's maximum width can beinserted through the coronary artery and into the myocardium.Preferably, the end of the conduit extending into the left ventricleincludes a retaining means. Once the resistance of the retaining meansis felt by attempting to withdraw the conduit, the excess length of theconduit extending out of the myocardium and through the coronary arteryis cut off.

The conduit 400 with valve 422 of the present invention preferablyadjusts to the changing width of the myocardium 16 during the heartcycle. FIGS. 26A and 26B illustrate another example of the conduit 400provided by the present invention wherein the inlet end 412 is flared438 and the outlet end 414 have projections 442 which slightly penetrateinto the area of the myocardium 16 surrounding the channel 42. Duringsystole, the thickness of the myocardium 16 is near its greatest duringthe heart cycle. As illustrated in FIG. 26A, the outlet end 414 of theconduit extends slightly into the coronary artery 26 and is retained inpositioned by being anchored to the exterior side 18 of the myocardium.The length of the conduit 400 is predetermined so that the inlet end 412of the conduit also extends slightly into the left ventricle 20 when themyocardium 16 is thickest during the heart cycle. Optionally, the inletend 412 can be flared 438 so as to further assure retaining the interiorside 24 of the myocardium to provide at least a slight extension of theinlet end 412 into the left ventricle 20. During diastole, the thicknessof the myocardium 16 decreases. As illustrated in 26B, the outlet end414 is anchored on one side of the conduit allowing the remainder of themyocardium to slide along the longitudinal axis 416 of the conduit. Theinlet end 412 is not specifically anchored and is free to extend furtherinto the left ventricle 20 during diastole.

The present invention provides other means for adjusting the conduit 400to the changing width of the myocardium 16 during the heart cycle. FIG.27 illustrates the conduit 400 with at least a two telescopingcomponents 444, 446 which slidably insert into one another as indicatedby arrow 445. Both the inlet end 412 and the outlet end 414 retain themyocardium in the desired position by anchoring the ends withprojections 442 to the interior side 24 and exterior side 18 of themyocardium, respectively. As the heart cycles, the component 446 slideswithin component 444 in a telescoping manner to adjust to the changingthickness of the myocardium. The length of the telescoping components444, 446 are predetermined so that they remain within each other allthrough the heart cycle.

Other examples of means for adjusting the conduit 400 to the changingwidth of the myocardium 16 during the heart cycle include theillustration in FIG. 28 which provides the conduit 400 with an accordionsection 456 which expands and contracts in a longitudinal direction asindicated by arrow 457 while providing resistance against radialcompression. Each end 412 and 414 retain the myocardium in the desiredposition by anchoring the ends with projections 442 to the interior side24 and exterior side 18 of the myocardium, respectively. As the heartcycles as indicated by arrow 452, the two ends 412, 414 move towardseach other during diastole and away from each other during systole withthe accordion section 456 respectively contracting and expanding in alongitudinal direction.

Alternately, FIG. 29 illustrates another accordion section 458 whichreversibly expands in a latitudinal direction. Each end 412 and 414retain the myocardium in the desired position by anchoring the ends withprojections 442 to the interior side 24 and exterior side 18 of themyocardium, respectively. As the heart cycles, the two ends 412, 414move towards each other during diastole and away from each other duringsystole with the accordion section 458 respectively contracting andexpanding in a latitudinal direction as indicated by arrows 460. Thelatitudinal accordion section 458 not only maintains and regulates bloodflow through the channel, but also provides a temporary reservoir ofblood in the accordion section 458 itself. The valve 422 can be placedat either end 412, 414 or valves placed at both.

Another example of the adjusting means of the present invention isillustrated in FIG. 30 wherein the conduit 400 includes at least twocomponents 448, 450 which form a body 402 which is discontinuous. Eachend 412 and 414 retains the myocardium 16 in the desired position byanchoring the ends with projections 442 to the interior side 24 andexterior side 18 of the myocardium, respectively. The valve 422 can beincluded in either component 488 or 450. With the components 448, 450positioned perpendicular to the myocardium width, the two components448, 450 move towards each other during diastole and away from eachother during systole when the heart cycles as indicated by arrow 452.Without support from either component 448, 459, a section 454 of thechannel between the two components 448, 450 is self-maintained in theopen position.

FIG. 31 illustrates an example of an adjusting means wherein the conduit400 includes a body 402 made of a continuous coil 462 which expands andcontracts along its longitudinal axis to accommodate the changingthickness of the myocardium 16 during the heart cycle while resistingradial compression. The outer periphery 464 of the coil 462 slides alongthe face 466 of the myocardium defining the channel 42. The coil 464 isanchored to the myocardium 16 at the inlet end 468 and outlet end 470 byprojections 472 which are supported by rings 474 connecting torespective ends of the coil 464. As the coil 462 expands, gaps 476 areformed between the outer periphery 464 of individual spirals or the gaps476 increase in size if the gaps already exist when the coil 462 is atits maximum level of relaxation during systole. Should the face 466 ofthe myocardium adhere to the outer periphery 464 of one or moreindividual spirals, either immediately after insertion into the channelor as a long-term effect, the remaining spirals provide expansion bymoving along the longitudinal axis.

The present invention provides conduits with a variety of configurationsemphasizing a non-obtrusive, non-traumatic connection into the coronaryartery. As illustrated in FIG. 32, a T-shaped conduit 490 includes abranch 492 allowing the continued flow of blood or prevents the stasisof blood proximal to the conduit in the coronary artery 26. FIG. 33illustrates a hook-shaped conduit 494 having a right-angle bend towardthe direction of desired blood flow. The outer periphery 496 of theconduit outlet end can be sized to have the coronary artery dilated overits edge or can be smaller than the diameter of the coronary artery.FIG. 34 illustrates a hybrid, synthetic/natural conduit 497 whichincludes a section of vascular tissue 498 attached to a syntheticsegment 499. The vascular tissue 498 is attached 495 to the wall 493 ofthe coronary artery by conventional closure means such as suturing. Inthis embodiment, no section of the conduit 497 extends into the coronaryartery.

The present invention also provides a naturally valved conduit such as avein or other vascular tissue which is preferably autologous. A conduitmade from the vein can be all natural or include synthetic materials incombination with the vein. As illustrated in FIG. 35, a preferredcombination conduit 500 combines a vein 502 which is at least partiallysupported by a synthetic cage 504 having an elongated body 506 with acylindrical or tubular shape and longitudinal members 508 having anexterior surface 510 and an interior surface 512. The cage 504 definesan interior space 514. The body 506 includes end members 516 connectedto the longitudinal members 508. The cage 504 includes projections 518which, as previously described, retain the conduit 500 in the desiredposition with the myocardium.

The vein 502 is extended along the interior surface 512 through theinterior space 514 of the conduit. The ends 520 of the vein 502 arestretched over end members 516 and back in the reverse direction tosecure the vein 502 to the cage 504. Optionally, a suture can be placedthrough the end 520 and the wall 528 of the vein. The vein 502 definesan inlet end 522 for receiving blood from the left ventricle or otheroxygenated blood source and an outlet end 524 for delivering theoxygenated blood to a selected site such as a coronary artery or vein.

The present invention regulates the flow of blood through the conduit500 utilizing the flaps and wall movement of the vein which areinherent, natural properties of the vein 502. The natural valvingfunction of the vein 502 is preserved by allowing the wall 528 of thevein to move towards itself or substantially collapse upon itself asindicated by arrows 526.

Another embodiment of the combination conduit 500 is illustrated in FIG.36. The cage 504 includes a second pair of end members 530 spaced in aparallel relationship to the end members 516 and connected to thelongitudinal members 508. Each end 520 of the vein 502 is inserted in apress fit between one of the end members 516 and second end members 530to secure the vein 502 to the cage 504. Other means of securing the vein502 to the cage 504 are also suitable such as be suturing the ends 520of the vein to the end members 516 with a continuous suture or aplurality of individual sutures. FIG. 36 also illustrates anotherexample of positioning the vein 502 along the exterior side 510 of thecage. As indicated in phantom 528A, the wall 528 moves toward itself orsubstantially collapses upon itself to preserve the natural valving ofthe vein 502.

The present invention provides other types of valves for regulating theflow of blood through a conduit or a self-maintained channel. One valvetype, as used in the Examples herein, is similar to a Starling resistorand illustrated in FIG. 37. The conduit 550 includes a rigid, elongatedbody 552 having an inlet end 554 which extends into the left ventricle20. The body 552 extends substantially through the myocardium 16. On theoutlet end 556 of the body is attached a valve 558 having a tubular body560 made of a pliable material which extends into the coronary artery 26distal to the blockage 28. The pliable material can be a section ofvein. The tubular body 560 is sufficiently flexible to collapse onitself. During systole, blood flows out of the outlet end 556 into thecoronary artery. As the cycle of the heart approaches diastole, thepressure of the blood flowing from the outlet end 556 decreases to thepoint where the pliable body 560 collapses which minimizes the reverseflow of blood from the coronary artery 26 back into the left ventricle20. Optionally, a cage 548 can be inserted into the coronary artery 26in the area of the tubular body 560 to assist in preventing the collapseof the artery in that area.

Another example of the valves provided by the present invention isillustrated in FIGS. 38A and 38B. A conduit 560 extends completelythrough the myocardium 16 and slightly into the left ventricle 20 andthe coronary artery 26. The conduit 560 includes at least one segment562 that is made of a pliable material which resists compression bysmall radial forces but which collapses as seen in FIG. 38B during aportion of the heart cycle. The conduit 560 is orientated at an obtuseangle to the interior side 24 and exterior side 18 of the myocardium andto the direction of change in the thickness of the myocardium. Becauseof the conduit's 560 orientation within the myocardium 16, the forcesapplied by the surrounding myocardium as it contracts and relaxes duringthe cycle of the heart change the both the length and diameter of theconduit 560 as generally illustrated in FIG. 38B. As a result, the flowof blood is minimized into the left ventricle 20 during the cycle of theheart.

As described above, the present invention provides a self-maintainedchannel 600 defined by a face 602 of the myocardium 16 as illustrated inFIG. 39. The channel 600 extends completely through the myocardium 16 ina perpendicular direction from the left ventricle 20 on the interiorside 24 to the coronary artery 26 on the exterior side 18. The channel600 is created by removing tissue so that it remains at least partiallyopen during the cycle of the heart.

Preferably, the self-maintained channel 600 includes a valve 604inserted within the channel as illustrated in FIGS. 39 and 40. The valve604 includes interleaved flaps 606 supported on a body 608. The valve604 is not associated with a conduit. The width of the body 608 ispreferably the minimum size required to provide support and orientationfor the flaps 606 and not particularly to maintain the channel 600 open.The flaps 606 are set to open during positive pressure exerted by bloodflow in the direction from the left ventricle 20 to the coronary artery26. Negative pressure or blood flow in the reverse direction at leastpartially closes the flaps 606 to minimize the flow of blood to the leftventricle 20.

The body 608 includes a periphery 610 having a thread 612 integrallyformed along the periphery. The thread 612 includes a starting edge 614for engaging the face 602 and slightly dilating the diameter of themyocardium 16. As the periphery 610 is rotated, the starting edge 614assists the advance of the thread 612 into contact with the face 602 ofthe myocardium. The thread 612 can slightly embed itself or slightlypenetrate into the face 602 of the myocardium to retain the valve 604 inthe self-maintained channel 600.

Another example of a mechanical means for regulating blood flow is touse a material in place of the flaps 606 which is semi-permeable toblood flow. The semi-permeable material can allow the blood to flow fromthe left ventricle while minimizing the reverse flow of blood.

The present invention also provides self-maintained channels whichregulate the flow of blood without a synthetic valve as illustrated bythe examples in FIGS. 41 and 42. Self-maintained channel 620 extendscompletely through the myocardium 16 from the left ventricle 20 to thecoronary artery 26. The channel 620 includes two segments 622 and 624which are orientated at an obtuse angle to the interior side 24 andexterior side 18 of the myocardium, respectively. A third segment 626connects to the other segments 622, 624 and is orientated in a generallyparallel direction relative to the sides 24, 18 of the myocardium and aperpendicular direction to the change in the thickness of themyocardium. Because the orientation within the myocardium of the twosegments 622, 624 and third segment 626 are different, each of thesegments is affected differently by forces applied by the surroundingmyocardium as it contracts and relaxes during the cycle of the heart.The forces from the myocardium can change both the length and diameterof the segments 622, 624, and 626. As a result, the flow of blood isminimized into the left ventricle 20 during the cycle of the heart. Itshould be noted that arrows indicate only a general movement of themyocardium 16 in changing thickness during the heart cycle. There areforces experienced during the heart cycle within the myocardium 16 whichare not strictly orientated perpendicular to the coronary artery andleft ventricle.

Another example of a self-maintained channel which regulates the flow ofblood therethrough with the natural rhythmic cycle of the heart isillustrated in FIG. 42. The self-maintained channel 640 includes a bowedor curved configuration which extends completely through the myocardium16 from the left ventricle 20 to the coronary artery 26. With properorientation of the bowed configuration between the interior side 24 andexterior side 18 of the myocardium, the forces applied by thesurrounding myocardium as it contracts and relaxes during the cycle ofthe heart can be advantageously used to regulate the flow of bloodthrough the channel 640. The forces from the myocardium can change boththe length and diameter of the channel 640. As a result, the flow ofblood is minimized into the left ventricle 20 during the cycle of theheart.

EXAMPLES

Two sets of experiments utilizing animals were designed to evaluate theacute functionality of the inventive methods. Each experiment wasperformed on a beating heart. No type of temporary assist or heart-lungbypass technique was utilized. Anesthesia was maintained with oxygenadministration in accordance with conventional protocol. ECG wasmonitored and an arterial monitoring catheter was placed in the leftinternal mammary artery for assessment of blood pressure.

The first set of experiments was carried out on seven female Yorkshirepigs weighing 30-35 kg. On four of the pigs, a formal sternotomy wasused and in the other three pigs, a left anterior 4^(th) intercostalspace thoracotomy was used. A prototype conduit was introduced into theleft ventricle through a formal sternotomy with the other end of theconduit introduced into the left anterior descending coronary arterythrough cannualation. The left anterior descending coronary artery wasthen tied proximally. In this set of experiments, blood flow wasdelivered to the proximally occluded left anterior descending arteryfrom the left ventricular chamber through a valved conduit, there beingno other blood supply to the left anterior descending coronary artery.

Several different types of inventive valves were incorporated within theconduit. These valves consisted of a fine penrose tube or an IMA veinsuspended between two ports in a chamber which could be pressurized. TheIMA vein would be harvested shortly before and have about a 2 cm lengthwith one or two valves. When connected in this fashion, blood passed ina continuous path from the left ventricular chamber via the penrose tubeor vein into the left anterior descending coronary artery. Thesurrounding chamber could then be pressurized to any pre-determinedlevel and in this way, the penrose tube or vein would collapse andprevent backflow when left ventricular pressure fell below thepressurized chamber level. The penrose tube or vein functioned in amanner commonly referred to as a “Starling resister” similar to thatillustrated in FIG. 20.

Another valve type employed a small penrose tube or a vein segment whichwas suspended from only one port in a non-pressurized chamber with asecond opening in the chamber allowing continuity of blood flow from theleft ventricle to the left anterior descending artery. Each harvestedvein graft was inserted between the two catheters, creating a valvedconduit approximately 15 mm long with an overall length of about 10 cmfor complete external pathway. In this embodiment, any attempt atbackflow of blood to the left ventricular chamber would cause collapseof the penrose tube or vein segment and occlude the backflow port.

In the seven pigs, Doppler flow measurement revealed both systolic andsome diastolic flow in the left anterior descending coronary artery.Blood flow was confirmed by miniature Doppler on the distal coronary andvein graft and the flow pattern was about systolic (80%), diastolic(20%). There was no obvious demarcation of an ischemic zone distal tothe left anterior descending coronary artery ligation nor werearrhythmias or an observable decrease in left ventricular contractionnoted. The inventive conduit was left in place from 30 min. to 1 and ½hours.

With occlusion of the conduit carrying blood from the left ventricularchamber, all of the hearts fibrillated within 3-5 minutes. This resultindicated that the ventricular supply of coronary blood was essentialand provided for normal function for the duration of the experiment.

The second set of experiments were designed to evaluate the net coronaryflow per minute whether delivered in systole or diastole, under controlconditions and compared these to the net coronary flow in mL/mindelivered from the left ventricle as the only source (all proximalcoronary arteries having been ligated.) In this set of experiments sixYorkshire pigs weighing 30-35 kg underwent surgical sternotomy andcannulation of the coronary sinus—the common outflow of all coronaryblood flow. The left hemiazygous vein was ligated so that coronary sinusblood was not contaminated by the systemic circulation. Under controlconditions all blood flow emanating from the coronary sinus wascollected for a specific period of time and the mL of coronary bloodflow per minute calculated. A left ventricular conduit was thensurgically inserted into the left ventricular chamber from theepicardial surface and then connected to cannulas which had beeninserted into the left and right coronary os. When the left maincoronary artery and the right coronary artery were snared around theintroduced cannula the left ventricle was the only source for coronaryblood flow. In this experimental set-up, coronary blood flow thereforeoriginated from the left ventricle and passed through a prototypeconduit and valving system as described above into the right coronary osand left coronary os. Measurement of total coronary blood flow emanatingfrom the coronary sinus under this condition demonstrated no differencein net coronary blood flow per minute from the control condition. Withthe coronary artery ligated, net coronary blood flow per minuteoriginating from the left ventricular chamber via the inventive conduitwas also measured without a valve in place. These sets of experimentsdemonstrated that net coronary blood flow per minute was similar whetherdelivered via the aortic root under control conditions or from a leftventricular source via the inventive conduit.

Several clinical discoveries were made which further support thephysiologic viability of the inventive methods. There is a similarity ofphysiology to patients with Aortic Valve Insufficiency. The deliveryrequirements per beat are very small. Continuous flow is observed duringcoronary angiograms. The mean pressure within the myocardium isrelatively low compared to systolic perfusion pressure. The animalsexperienced no change in EKG and no change in heart wall motion. Therewas no change in flow characteristics of blood. The coronary arterialsystem was compliant and enabled diastolic perfusion.

Some conclusions may be drawn from other observations. The dynamicmotion of heart muscle and subsequent motion of the conduit may reducestasis which contributes to clot formation. The high velocity ofdelivery from the left ventricle to the coronary artery may reduceincidence of clot formation and resulting thrombosis (occlusion). Theshort length of the conduit (approximately 15 mm) may reduce the chanceof clot formation and thrombosis (occlusion).

In comparing the inventive left ventricle to coronary artery approach tothe conventional coronary perfusion approach, it was found that the sameamount of blood was being delivered across the myocardium to thecoronary sinus in both approaches. Compared to conventionaltransmyocardial revasculation techniques the present invention used muchlarger holes, enabled patency of the channel and demonstrated theheart's ability to tolerate this type of intervention with littleeffect.

The present invention provides significant advantages when compared tothe prior art relating to interventional procedures such as the abilityto improve long term patency rates and reduce the high rate ofretreatment. Furthermore, the present invention allows multiple vesselsto be treated. Compared to CABG surgery, the present invention is aless-invasive procedure which can be performed on a beating heart usingsmaller incisions for entry than normally required by conventionaltechniques. Also, harvesting an autologous graft may not be needed.

The present invention fulfills many needs found wanting in the priorart. Many patients were not candidates for percutaneous or CABG surgerybecause they could not be fully revascularized by the surgery. Thepresent invention significantly enlarges the population of potentialcandidates. Furthermore, the use of small ports between the ribs toprovide the revascularization provides an access site in the immediatevicinity of the selected site in the arterial vascular system and avoidsthe use of a sternotomy and/or a thoracotomy. The present inventionprovides access to the arterial vascular system on both sides of theheart such as the left anterior descending artery, circumflex artery,and as well as their tributaries.

As described, the present invention fulfills many clinical needs thatare currently unmet by the prior art. For example, many patients withcoronary artery disease are not amenable to CABG or percutaneoustreatment due to their extensive disease. However, this invention offersa comparable treatment alternative to conventional techniques allowingthese patients to receive care. Furthermore, the inventive approachprovides for methods and devices that allow for coronaryrevascularization procedures to be performed through small holes insteadof a chest incision. The present invention provides access to thearterial vascular system allowing for all vessels of the heart to berevascularized.

The present invention also provides for partial revascularization orincreased flow by having a self-maintained channel or conduit without avalve. In this embodiment, a channel is created and maintained betweenan oxygenated blood source and a site selected in the arterial vascularsystem. The channel does not incorporate means for regulating the bloodflow therethrough. More particularly, when the selected site is distalto a substantial or complete blockage or occlusion, a self-maintainedchannel or conduit without a valve between the left ventricle andselected site provides significant, but not complete, revascularizationof the selected site and the surrounding area.

1. A method for increasing the flow of blood to a selected site in apatient's arterial vascular system of the heart, the method comprisingthe steps of: creating a channel for blood flow from an oxygenated bloodsource to the selected site in the arterial vascular system of theheart; maintaining the channel in an open position for blood flowthrough diastolic and systolic cycles of the heart; and regulating theblood flow in the channel to minimize blood flow from the coronaryvascular system to the blood source during diastole.
 2. The method ofclaim 1 wherein the creating step includes perforating and dilating thetissue surrounding the blood source to create the channel therein. 3.The method of claim 1 wherein the creating step includes removing tissueto form an aperture completely through the tissue surrounding the bloodsource to partially create the channel therein.
 4. The method of claim 1wherein the creating step includes exposing at least a portion of thepatient's heart for surgical access.
 5. The method of claim 1 whereinthe creating step includes advancing a delivery device to the tissuesurrounding the blood source.
 6. The method of claim 1 wherein the bloodsource is the left ventricle and the tissue surrounding the blood sourceis the myocardium.
 7. The method of claim 1 wherein the method includesmore than one blood source.
 8. The method of claim 1 wherein the methodincludes more than one site in the arterial vascular system.
 9. Themethod of claim 1 wherein the method includes selecting a site in thearterial vascular system distal to an obstruction therein.
 10. A methodfor performing a transmyocardial coronary revascularization procedurefor the treatment of coronary atherosclerosis caused by an obstructionin the arterial vascular system, the method comprising the steps of:creating a channel for blood flow from an oxygenated blood source to thearterial vascular system distal to the area of obstruction; maintainingthe channel in an open position for blood flow through the diastole andsystole cycles of the heart; and regulating the blood flow in thechannel to minimize blood flow from the arterial vascular system to theblood source during the diastolic cycle of the heart.
 11. The method ofclaim 10 wherein the creating step includes perforating and dilating thetissue surrounding the blood source to create the channel therein. 12.The method of claim 10 wherein the creating step includes removingtissue to form an aperture completely through the tissue surrounding theblood source to partially create the channel therein.
 13. The method ofclaim 10 wherein the creating step includes exposing at least a portionof the patient's heart for surgical access.
 14. The method of claim 10wherein the creating step includes advancing a delivery device to thetissue surrounding the blood source.
 15. The method of claim 10 whereinthe blood source is the left ventricle and the tissue surrounding theblood source is the myocardium.
 16. The method of claim 10 wherein themethod includes more than one blood source.
 17. The method of claim 10wherein the method includes more than one site in the arterial vascularsystem.
 18. The method of claim 10 wherein the method includes selectinga site in the arterial vascular system distal to an obstruction therein.19. A method for treating an obstruction in a patient's cardiovascularsystem using a non-expandable conduit made of biocompatible material,the method comprising the steps of: inserting the conduit completelythrough the myocardium of the patient's heart with one end of theconduit extending into the left ventricle and the other end of theconduit extending into the arterial vascular system distal to the areaof obstruction; maintaining the conduit in an open position for bloodflow through the diastolic and systolic cycles of the heart; regulatingthe blood flow in the channel to minimize blood flow from the arterialvascular system to the left ventricle during the diastolic cycle of theheart.
 20. The method of claim 19 wherein the inserting step includesperforating and dilating the tissue surrounding the blood source tocreate the channel therein. 21-38. Canceled